Call it yet another example of collateral damage from the problems in the U.S. subprime mortgage market.

Simply put, it's costing banks and other lenders more to raise the money they use to finance mortgages, and they're passing the cost on to people buying homes and refinancing existing mortgages.

That's why the posted major bank rate for five-year mortgages is as much as 7.44 per cent right now, which is the highest level since May, 2002, and why new variable-rate mortgages are becoming more expensive almost by the day (existing variable-rate mortgages are unaffected).

A discount of 0.9 of a percentage point off the prime rate used to be a good but attainable deal for borrowers. Today, mortgage broker websites - remember, these guys have access to many lenders - are showing best deals of prime minus 0.6 or 0.75 points.

Alex Haditaghi, CEO of Mortgagebrokers.com, said his contacts with bank representatives suggest that fully discounted five-year rates could go as high as 6.5 per cent from their current level around 6 per cent. He also warned maximum discounts on variable-rate mortgages may shrink further. "Two banks have given the heads-up that if you want to lock up your clients, do it now because by Nov. 15 you're going to see us go to 0.5 below prime."

If you're looking for a house or have a mortgage expiring in the next three or four months, you should talk to lenders right now to lock in the best possible rate. A 120-day rate guarantee is pretty common these days and it offers a shield against further rate increases. Shopping around for rates is more important than ever today because lenders are all taking different approaches to the current mortgage-market uncertainty.

Borrowing costs for mortgages track rates in the bond and money markets, which in turn are a reflection of sentiments about where the economy and inflation are headed. Today, inflation is contained in Canada and recently there have been economic forecasts that call for slower but still solid growth in 2008. Add it all up and you have an environment where rates should be holding tight, not rising.

The reason why this isn't happening is related to the same junk mortgages in the United States that helped pushed the stock market into its summer slump. These mortgages were packaged into investments that were widely purchased by banks, investment dealers and other institutional investors who are now a lot more risk-sensitive than they were before.

One way for investors to manage risk is to demand higher returns, and that's in fact what Canada's lenders are running into when they issue the short-term securities they use to finance variable mortgage loans. If the banks have to pay more, they have to charge more to keep up their profit margins. So it is that we have the incredible shrinking variable-rate mortgage discount in Canada.

Fixed-rate mortgage rates have jumped recently in what can best be described as a catch-up to this past summer's financial market troubles. You'll see this not only in the five-year rate, but also in posted big bank one-year rates that are as high as they've been since early 2001.

Benjamin Tal, senior economist at Canadian Imperial Bank of Commerce, said lenders held mortgage rates steady through August and September, and even cut them a bit at one point. Then, with bond yields on the rise earlier this month, a decision was made to bump up five-year rates significantly. "You might say that consumers got an extra two months of relatively cheap rates," Mr. Tal said.

The biggest victims of the U.S. subprime mortgage situation here in Canada are people with poor credit histories, new immigrants and the self-employed. Their mortgage applications are being scrutinized more carefully than six months ago, and some people are being offered loans at higher rates or are being rejected.

Tighter lending rules are going to be a fixture for a while, but higher mortgage rates may prove temporary. CIBC's Mr. Tal said the factors making variable-rate mortgages more expensive will slowly die away, and he argued that the state of the economy in both Canada and the United States doesn't suggest much risk of rising rates. "Over the next six months, it's very reasonable to think that rates will be stable, with a bias downwards."

If you're in the market for a home, get a rate guarantee and then keep an eye on the housing market. It's been hot, like, forever and high rates are just the sort of thing to cool things down.